Pump



March 3, 1942.

A. H. 'ORCUTT PUMP Filed Feb. 14, 1959 2 Sheets-Sheet 1 i is Patented Mar. 3, 1942 UNITED STATES PATENT OFFICE PUMP I Arthur Hitchcock'Orcutt, Birmingham, England, assign'or'to The Gear Grinding Company Limited, Birmingham, England v I A pplicationFebruary 14, 1938, Serial No. 190,528

. In Great Britain Februa'ry25, 1937 plungers or other fluid operated parts of the machine by a pump.

The pumps employed are usually designed to deliver the fluid at as uniform pressure as possible, but no pump is capable of providing a perfectly uniform pressure, that is to say a pressure which is free from pulsations, and consequently various devices have been employed in conjunction with the pump for smoothing out the pressure pulsations. The need for uniform pressure free from pulsation is especially desirable in machine tools intended to produce a fine and accurate finish on the work pieces, as small and rapid pressure pulsations in the working fluid result in a rippled appearance on the surfaces of the work pieces.

The object of the present invention is to provide improved means for minimizing pressure pulsations in the working. fluid.

The invention comprises the combination of a closed chamber of large capacity and having rigid walls, a pump for supplying working fluid to the said chamber, means for conveying fluid from the chamber to the parts of the machine to be operated, and a by-pass situated between the pump and the chamber, the pump being adapted to supply fluid in excess of the requirements of the machine to be operated, and the by-pass serving to return the excess fluid to a reservoir which supplies the pump.

In the accompanying sheets of explanatory drawings:

Figure 1 is a plan of means constructed in accordance with the invention for supplying pressure fluid to a metal cutting or grinding machine.

Figure 2 is a section on the line 2-2 of Figure 1.

In carrying the invention into efiect as shown, I form in the bed a of the machine to be operated a closed chamber b of large capacity. The walls of this chamber are made rigid so as to avoid vibrations being imparted to the fluid by small distortions of the walls under the action of the fluid pressure. In the example shown two adjacent walls of the chamber b also serve as walls for a reservoir or sump comprising intercommunicating parts (2, d, formed in the bed a of the machine. The part c of the sump contains the pump e which may be of any COIIVEII.

ient form. The pump is driven by a spindle n to which motion is imparted by any convenient power-operated means. The delivery end of the pump is connected to the chamber 1) by a passage f, and the inlet of the pump is provided with a filter g. Between the delivery end of the pump e and the chamber b I arrange a by-pass h which discharges into the sump and is controlled by an adjustable choke i of any convenient form, the choke'being adjusted to maintain the desired fluid pressure in the chamber b when the pump is working. The fluid is conveyed from the chamber b to the fluid actuated parts of the machine by ,a pipe or pipes as 7', andpreferably the chamber b is also provided with a relief valve is for limiting the pressure of the fluid in the chamber by connecting the latter to a pipe m leading to the part d of the sump.

The pump e is adapted to deliver fluid in excess of that required by the machine to be op-.

erated and the excess is allowed to return to the inlet of the pump through the by-pass h and the sump parts 0, d. When the excess is sufficient little or none of the pressure pulsations caused by the action of the pump e are felt in the chamber b, as they are smoothed out at the by-pass h. The fluid in the chamber b is relatively dead, and consequently the fluid is supplied to the working parts of the machine at a Patent is:

1. Means for supplying pressure fluid to fluidoperated machine tools such as metal grinding or cutting machines, comprising the combination of a closed chamber having an inlet and at least one outlet at diflerent positions, and having rigid walls, the chamber being of large capacity, and its outlet being arranged so that the chamber can be completely filled with working fluid, a reservoir for the fluid, a pump for supplying Working fluid from the said reservoirto the inlet of the said chamber, means for conveying fluid from the outlet of the said chamber to the parts of the machine to be operated, and a constantly open by-pass situated between the delivery side of the said pump and the inlet of the said chamber, the said pump being adapted to supply fluid in excess of the requirements of a the machine to be operated, and the said bypass serving to return the excess fluid to the said reservoir.

2. Means for supplying pressure fluid to fluidoperated machine tools such as metal grinding or cutting machines, comprising the combination of a closed chamber having an inlet and at least one outlet at different positions, and having rigid walls, the chamber being of large capacity, and its outlet being arranged so that the chamber can be completely filled with working fluid, a reservoir for the fluid, a pump for supplying working fluid from the said reservoir to the inlet of the said chamber, means for conveying fluid from the outlet of the said chamber to the parts of the machine to be operated, a constantly open by-pass situated between the delivery side of the said pump and the inlet of the said chamber, and an adjustable choke for controlling the said by-pass, the said pump being adapted to supply fluid in excess of the requirements of the machine to be operated, and the said by-pass serving to return the excess fluid to the said reservoir under the control of the said choke.

3. Means for supplying pressure fluid to fluidoperated machine tools such as metal grinding or cutting machines, comprising the combination of a closed chamber having an inlet and at least one outlet at different positions, and having rigid walls, the chamber being of large capacity and its outlet being arranged so that the chamber can be completely filled with working fluid, a reservoir for the fluid, a pump for supplying working fluidfrom the said reservoir to the inlet of the said chamber, means for conveying fluid from the outlet of the said chamber to the parts of the machine to be operated, a passage interconnecting the said pump and the inlet of the said chamber, a constantly open bypass communicating with the said passage, and

I an adjustable choke for controlling the said bypass, the said pump being adapted to supply fluid in excess of the requirements of the machine to be operated, and the said by-pass serving to return the excess fluid to the said reservoir under the control of the said choke.

ARTHUR HITCHCOCK ORC-U'IT. 

